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Science Today: The Next Generation of RF Power Sources

Continuing the tradition of extending the state-of-the-art of klystron design, the Klystron and Microwave Department is currently working on the next generation of accelerator radio frequency (RF) power sources to power the International Linear Collider (ILC): the Sheet Beam Klystron (SBK).

An SBK is a klystron that uses a broad sheet-like electron beam rather than the intense round beams used in traditional klystrons. This type of beam allows the device to operate at lower voltage and higher current than conventional klystrons while having the low beam current densities required for high operating efficiencies. Furthermore, the wide beam geometry allows for greater internal surface area of the klystron reducing beam interception and circuit heating problems that have plagued earlier conventional klystrons. Another means to this same end is the multi-beam klystron (MBK) being produced by industry and used in the current ILC baseline design. The SBK is potentially a lower cost and higher reliability alternative to the MBK.

The SLAC L-band SBK (LSBK) design builds upon previous work done at higher frequencies, two W-band SBKs, the second of which is being prepared for test as this article is written, and an X-band SBK for the room temperature Next Linear Collider (NLC) that did not progress past the design stage.

The SLAC program plan entails building a beam test device consisting of an electron gun and anode with removable downstream diagnostic test sections that will be used to verify the complex beam formation and transport computer simulations. This first device is scheduled for test in the second quarter of FY08. Following closely, in the third quarter of FY08, will be the construction and test of a full power klystron. Successful completion of this project will constitute a major breakthrough in high power microwave tube design benefiting a myriad of high energy physics and industrial applications.

The Klystron and Microwave Department LSBK design team is headed by Program Manager Erik Jongewaard, who leads the mechanical engineering design efforts of Andy Haase, David Martin and Rich Schumacher; and Daryl Sprehn, who leads the electrical engineering design efforts of Alex Burke and Aaron Jensen. Mechanical design, drafting, and checking is handled by Oscar Frener, Richard Gonzales, Linda Sewell and Ng Wing.